Climbing Stairs Just Got Easier with Energy-Recycling Steps

Device is easier on knees and ankles than conventional stairs

By
Jason Maderer | July 12, 2017
• Atlanta, GA

A demonstration of the steps, which can be placed on existing staircases.

Researchers at Georgia Tech and Emory University have created a device that makes walking up and down stairs easier. They’ve built energy-recycling stairs that store a user’s energy during descent and return energy to the user during ascent.

The spring-loaded stairs compress when someone comes down the stairs, saving energy otherwise dissipated through impact and braking forces at the ankle by 26 percent. When going up, the stairs give people a boost by releasing the stored energy, making it 37 percent easier on the knee than using conventional stairs. The low-power device can be placed on existing staircases and doesn’t have to be permanently installed.

Each stair is tethered by springs and equipped with pressure sensors. When a person walks downstairs, each step slowly sinks until it locks into place and is level with the next step, storing energy generated by the user. It stays that way until someone walks upstairs. When a person ascending the stairs steps on the sensor on the next tread up, the latch on the lower step releases. The stored energy in the spring is also released, lifting up the back leg.

The paper is currently published in the journal Public Library of Science PLOS ONE. The authors say the initial idea was to use energy-recycling prosthetic shoes to help people going up stairs.

“Unlike normal walking where each heel-strike dissipates energy that can be potentially restored, stair ascent is actually very energy efficient; most energy you put in goes into potential energy to lift you up,” said Karen Liu, an associate professor in Georgia Tech’s School of Interactive Computing. “But then I realized that going downstairs is quite wasteful. You dissipate energy to stop yourself from falling, and I thought it would be great if we could store the energy wasted during descent and return it to the user during ascent.”

Walking down stairs is like tapping the breaks of your car while revving the engine," said Ting. "Your legs use a lot of energy bracing each steop to avoid falling too fast. Our stairs store that energy rather than wasting it."

The researchers didn’t expect, prior to designing the device, that the stairs would actually ease the impact of going downstairs.

“The spring in the stairs, instead of the ankle, acts as a cushion and brake,” said Yun Seong Song, who built the device as a postdoctoral researcher at Georgia Tech. He’s currently an assistant professor at Missouri University of Science and Technology. “The gentle downward movement alleviates work by the trailing ankle, which is what keeps you balanced and prevents you from falling too fast on normal stairs.”

Liu initially got the idea for the project when she attended a conference and saw an ankle brace that stored and released energy. Her 72-year-old mother has no problems walking but has difficulty climbing steps, and Liu knew she wouldn’t wear special sneakers just for stairs. So she decided to make smart stairs that act like the shoe.

“Current solutions for people who need help aren’t very affordable. Elevators and stair-lifts are often impractical to install at home,” Liu said. “Low-cost, easily installed assistive stairs could be a way to allow people to retain their ability to use stairs and not move out of their homes.”

“Maintaining mobility is very much a use-it-or-lose-it thing. It’s important to keep people walking and independent through injury and aging to maximize quality of life,” said Ting.

The researchers think the temporary stairs could also be helpful for those recovering from surgery or pregnant women — people who only need help for short periods of time and don’t need to permanently alter their homes.

The researchers are looking for partners to extend the project, which currently runs on a staircase with only two steps and can be used by just one person at a time. It was supported by the National Science Foundation (EFRI-1137229).

Additional Photos

Each stair is tethered by springs and equipped with pressure sensors. When a person walks downstairs, each step slowly sinks until it locks into place. When a person ascending the stairs steps on the sensor on the next tread up, the latch on the lower step releases.

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School of Earth and Atmospheric Sciences

The Next Frontiers in Space

A new report, written by The Planetary Society, says the clock is ticking for exploration on Mars. Quickly. As the group notes, NASA only has one mission in development for the Red Planet — the Mars 2020 Rover. More is needed, according to the Society, particularly an updated orbiter and a rover that can land and retrieve samples dug up by the 2020 robot. James Wray in the School of Earth and Atmospheric Sciences is a science team member on most of NASA and the European Space Agency’s missions currently active on Mars.

I’m excited and re-energized by our President’s support of planetary exploration, from his inaugural address to his proposal of an all-time record(!) budget for NASA’s Planetary Science Division. The proposed funding will enable the long-overdue launch of a robust program to explore ocean worlds in the outer solar system, beginning with Jupiter’s most fascinating moon, Europa. For far too long, NASA has obeyed Arthur C. Clarke’s fictional admonishment on Europa in his 2010: Odyssey Two: “Attempt no landings there.” And yet, we must! And, someday soon, we will.

NASA’s budding ocean worlds program can benefit from many lessons — mostly positive, and perhaps a few negative — from its extremely productive Mars Exploration Program. I can directly attest to the synergies enabled by a well-integrated series of orbital and surface missions. Maintaining this degree of complementarity requires careful planning, and (as The Planetary Society notes) the time is nigh for action to ensure that our expanded exploration of the outer solar system does not leave our samples — and our science — stranded at Mars. We do not want NASA’s next (sample-caching) rover to be nicknamed “Watney.”

Two years ago, I coauthored a NASA-solicited report on the objectives that a new Mars orbiter could address in the early 2020s. Such a robotic mission not only could follow up on new evidence for modern liquid flows on Mars, but also represents one way to fulfill the scientific community’s consensus top priority for Mars exploration in this decade: returning carefully selected samples from the surface of Mars. But there’s another way to achieve this. As Neil Armstrong and Buzz Aldrin did for the moon, human astronauts could return the first samples from Mars, whether via their own geological survey of the planet or by retrieving samples robotically cached prior to their arrival. And therein lies perhaps the biggest question for NASA’s near future: how soon will astronauts be visiting Mars?

To answer this question, I am eagerly awaiting the President’s appointment of a new NASA Administrator. The agency has embarked on a multi-decade journey to Mars, requiring still much new technology development. But the President has argued for a more accelerated timeline, and if Apollo is any guide, then the proper funding and focus can make anything possible. New leadership at NASA should be empowered to balance these visions and pursue a synergistic robotic-and-human program of exploration, taking full advantage of the unprecedented international interest in Mars. Half a dozen different government agencies and at least one private company are planning missions there in the next few years. NASA has provided an undisputed head start, representing the only nation thus far to safely land on and return science from the Red Planet (seven times!). Ad astra per Mars!